Process of slaking lime and lime-containing substances and certain novel products of said process.



No. 802,354. PATENTED OOT.1'7, 1905.

' 0. ELLIS.

PROCESS OF SLAKING LIME AND LIME CONTAINING SUBSTANCES AND CERTAIN NOVELPRODUCTS 0? SAID PROCESS.

APPLIOATION FILED JULY 18,1905.

WWNESSES IIIT S I PTN FI IUlEl.

(JARLETQN ELLIS, OF NEIV YORK, N. Y.

PROCESS OF SLAKING LIME AND LIME-CONTAINING SUBSTANCES AND CERTAIN NOVELPRODUCTS 0F SAID PROCESS.

Specification of Letters Patent.

Patented Oct. 17, 1905.

Application filed July 18,1905. Serial No. 270,193.

Be it known that I, CARLn'roN ELLIS, a citizen of the United States,residing in the city, county, and State of New York, have inventedcertain new and useful Improvements in Processes of Slaking Lime andLime-Containing Substances, also Certain Novel Products of said Process;and I do hereby declare the following to be a full, clear, and exact de'scription of said process and products.

This invention relates to processes of slaking lime and lime-containingsubstances and to the products thereof.

It consists in a novel continuous process of slaking lime to a dryuniform powder of regulated hydration complete or incomplete to anydegree which may be desired; and the said invention also consists incertain novel products obtained by such incomplete hydration.

The desirability of being able to slake lime uniformly and rapidly andto a dry powder is well recognized; but the methods heretofore known foraccomplishing this end have been unsatisfactory, involving either slow,tedious, and expensive manual labor, or in the case of the manymechanical processes being incapable of yielding a uniform product suchas is necessary for good work. These difliculties and objections areobviated, however. by my invention, which comprises a continuous processof hydration capable of being conducted by machinery and of reducing thelime or lime-containing substances to a dry powder which is hydratedcompletely or to any desired percentage of incomplete hydration.

In another application for Letters Patent tiled July 13, 1903, SerialNo. 165,363, I have claimed a process of hydrating lime completely, saidprocess consisting in bringing together a stream of lime and a stream ofwater, the latter just suiiicient in quantity to transported without themany ditficulties and dangers incident to the transportation ofqulcklime, is ready for immediate mlxture with water and sand or othermaterials to make mortar, cement, &c., and when so mixed does notoccasion the production of heat, which is so annoying when quicklime isslaked, nor is there the delay due to waiting for the slaking to go onamatter of hours or days in some cases. It also permits the production asan article of manufacture of dry-mixed mortarthat is, a dry mixture oflime, sand, &c.-which is ready for use upon the addition of moisture,and the mixing of the dry hydrated lime with the sand, &c., involvesmuch less work than the mixing of the same ingredients when wet and maybe done with great thoroughness. For many purposes also it is desirableto use an incom pletely-hyd rated limethat is, limewhioh has been slakedto a point more or less short of complete saturation of its chemicalaflinity for water. This is the casein making mixtures of lime andcement, whether the latter be of the Portland, natural, slag, or othervarieties. Completely-hydrated lime,,even when in the form of a drypowder, usually contains or absorbs from the atmosphere an excess ofmoisture. If attempt be made, therefore, to mix such completely-hydratedlime with cement and to retain it in such mixed condition for anyconsiderable length of time, (as is unavoidable if such mixture is to betreated as an article of manufacture or an article of commerce,) thereis danger that the cement will take up the excess of moisture from thelime and set. This difficulty is avoided by the use, instead ofcompletly-hydrated lime, of partly-hydrated or short'slaked lime, thehydration of which is sufficiently incomplete to insure that there shallbe no excess of water present either at the time of mixing orsubsequently for an extended period as a result of absorption from theair. As will be shown hereinafter, however, this shortslaked lime,though incompletely hyd rated,has had its chemical a'l'linity for waterso nearly satisfied that it may be handled with substantially the samecase as completely-hydrated lime and with the same absence of thedilficulties, dangers, and inconveniences attendant upon the handling ofquicklime. The shortslaked lime does not heat objectionably upon theaddition of water, but when water is added slakes to complete hydrationvery quickly.

The use of short-slaked lime has the further advantage over the commonpractice in the making of mortar, 80s., of slaking quicklime completelyand then adding the other ingreclients to it, that on the addition ofwater the lime, particularly if it be fat, tends to become a smearyputty, which quality impedes thorough mixing and distribution of theingredients. Lean limes, on the other hand, if used in the ordinary wayjust referred to in the making of cement mortars, &c., are apt to takeup moisture with less speed than the cement itself, slaking aftersetting has begun and causing the cement to fail. By using theshort-slaked lime of the present inventionthat is to say, a lime slakedto approximately three-fourths to four-fifths of complete h v' dration acement mortar of much improved quality may be obtained and much betterresults as to impermeability to moisture realized. Moreover, the cementmortar formed of the short-slaked lime works easier and better.

In making lime mortars for plastic purposes, and particularly when usingmagnesian lime, I have found that the partially-hydrated lime worksbetter under the trowel than completely-prehydrated lime, which latterdoes not soften up well with water and forms a mortar which sticks tothe trowel, preventing dressing to a smooth surface. This difficulty isnot experienced with mortars made from the partially-hydrated orshort-slaked limes of the present invention. The short-slaked lime alsoforms a better ingredient of calcined or hard-wall plaster mixtures forsimilar reasons and also because the short-slaked lime does not give upmoisture to the plaster. For this reason the short-slaked lime makespracticable as an article of manufacture a ready-mixed plastercomposition requiring only the addition of water to fit it for use.

The incomplete hydration, toa regulated degree, of lime also forms aconvenient and valuable means of regulating the action of lime as acaustic, for which reason lime partly bydrated in accordance with myinvention may be used in depilatories, paint-removers, &c.

It is of course'obvious that in the partiallyhydrated limes thehydration, to whatever extent it may be carried, must be uniformthroughout the mass in order that uniform results may be obtained by theuser, also that the extent of the hydration must be perfectly under thecontrol of the operator and variable at will in order to enable him toobtain proclucts specially suited for different purposes and to make itpossible to furnish the same grade at all times, whatever the raw limeused.

The objects of my invention, therefore, are to hydrate lime in a simple,easy, and economical manner; to keep the degree of hydration completelyunder control and permit variation of such degree of hydration to anyex- .tent desired; to insure that the hydration,

whether partial or complete, shall be uniform throughout the masstreated; to make the process of hydration a continuous one, capable ofbeing carried out by automatic machinery; to produce superiorready-mixed cements and plasters, and to produce as an article ofmanufacture a dry, powdered, shortslaked lime hydrated to such degreethat it may be handled and transported with the same facility ascompletely-slaked lime and may be used with the same facility andwithout the objections and inconveniences which attend the use ofquicklime and which will give results superior in many cases to thoseobtainable from completely-hydrated lime and equal in all respects tothose obtainable from quickime.

In carrying out my process 1 cause the lime, which preferably is insmall fragments or in a pulverulent state, to move in a stream orcontinuous body through and beyond a zone of water-supply wherein waterflows into the lime in an amount regulated to produce the precise degreeof hydration desired, whether partial or complete. The water is alladded before any substantial hydration takes place, that it maypenetrate throughout the mass of lime before the pores of the latter aresealed.

by hydration of the exterior; but I do not mean by this that the watermust all be added in a single stream. To the contrary, the addition ofthe water may continue through a considerable zone or space traversed bythe moving stream or mass of lime, hydration not taking place, at leastto a material extent, un-

til the lapse of a certain time after the first addition of the water;but it is essential that the water necessary for the production of thedesired degree of hydration shall all be added and distributed wellthrough the mass before the pores are sealed by hydration, as otherwiseirregular results may be obtained. Af ter the lime passes from the zonein which the addition of water occurs the motion of the stream or bodyof lime is continued while hydration goes on, the conduit in which thisaction occurs being preferably a closed one, so that little or none ofthe moisture is lost by evaporation, the hydration taking place in thevapor produced by such hydration. Du ring the process of hydration themass of lime is preferably stirred, agitated, mixed, or worked bysuitable means. The hydration continues, as above described, until allfree water has disappeared and the union of the water with the lime iscomplete, as aresult of which action the lime will have been reduced toa dry powder, which latter is then discharged from the conduit in whichthe hydration has been conducted. The amount of water added will beregulated according to the quality of the lime treated and according tothe degree of hydration desired, all as dictated by experience. As iswell known, fat lime requires for complete hydration only aboutone-third of its weight of water, although in practice about half itsweight is customarily added, the excess compensating for loss byevaporation; but each particular brand of lime requires a slightlydifferent amount of Water in correspondence With its composition, fewlimes being pure calcium oxid and most limes containing magnesia ingreater or less amount. In each case, therefore, the volume of wateradded must be regulated by experience and by the observed composition ofthe finished slaked product.

The Water used may be heated, particularly when lean limes are treated,as the heating of the water accelerates the action. The operation beingconducted in a closed conduit, the heat produced by the reaction isretained, and the progress of the operation thereby greatly facilitated.The use of a closed conduit also prevents dissipation of lime-dust andkeeps the carbon dioxid of the air from contaminating the lime. 7

Portland and other cements and the hydraulic limes into which they gradeusually contain more or less free lime which requires to be slaked, asuniversally recognized, since being usually of the slow-slakingvarieties if allowed to remain unslaked until the cement is used it doesnot hydrate at oncewhen the cement is mixed with Water, but continues toabsorb water for lengthy periods of time, slaking completely only afterthe cement proper has set and by its swelling causing the concrete, &c.,to fail or weaken, according to its amount. The usual method of slakingthe free lime in cement and the like is either to allow the cement toweather by exposure to the air or by treating it in mechanical devices,whereby moistened air is forced to permeate it. Both of these methodsare unsatisfactory. By treating limy cements and the like by my process,as above described, and preferably by adding the Water in the form of aclustspray, the hydration of the contained lime may be effected quicklyand thoroughly. I intend in the following claims to include thehydration of lime as such and also when intermixed with or combined withother substances-such as cement, for example.

For the production as an article of manufacture or article of commerceof a shortslaked lime I have found hydration to from three-fourths tofour-fifths of complete hydration desirable. The product thus formed isa dry powder which may be stored in barrels, bags, &c., withoutsuffering deterioration by moisture from the air for long periods oftime, which may be handled with facility, and which does not liberateheat objectionably when moistened, but nevertheless softens readily whenmoistened, and is thus suitable for use as an ingredient of higlrgradeplasters, mor tars, cements, and the like.

Ready-mixed plasters, cements, mortars, as, may be formed by mixingshort-slaked lime slaked to the degree above specified or to otherdegrees, as found desirable, and mixed dry with plaster, cement, sand,&c., and these dry mixtures will remain dry and in condition for use forlong periods of time, because of the power of the short-slaked lime ofabsorbing moisture which might otherwise impair the quality of theplaster, cement, &c., and because the short-slaked lime contains noexcess of moisture, as full slaked lime often does, which excess ofmoisture may be imparted to the plaster or cement and cause prematuresetting thereof.

While I do not confine myself to the use of any particular miparatus forcarrying out my process, 1 have illustrated diagramatically in theaccompany drawing one form of apparatus for carrying out said process.

in said drawing, 1 designates a hopper from which the lime is fed to thehydrating apparatus by means of a suitable feeding device 2. indicatedin the drawing as a screw working in a trough. From said trough the limefalls through a chute i) into a trough 4:, along which it is movedbysuitable propelling means, such as'a screw 5, and in this conduit itreceives the water for h vdrati n, which water is de livered from asource of supply (not shown) by pipe 15, having a plurality ofjet-nozzles or spraying devices 16. The number and dis tribution ofthese spraying devices 16 is such that the water required for hydrationis all delivered to the lime in the conduit 4 before hydration has takenplace to any material extent, the screw 5 serving to distribute themoisture through the mass of lime by stirring the latter, as well asmoving it through the conduit. From conduit t the moistened lime fallsinto the closed conduit 6, in which the hydration goes on, the mass oflime being stirred and moved onward slowly by suitable means, such asthe conveyer 7. The conduit being closed, the vapor produced by thehydration is retained, as is the lime-dust produced, and the air isexcluded. in this way loss by evaporization is avoided, thereby avoidingvariation in degree of hydration due to variable loss of moisture byevaporation, while the exclusion of air prevents the entrance ofcarbonicacid gas. A very uniform and pure product is thereby insured.The amount of water supplied is completely under control by means of avalve in pipe 8 or other suitable means, and by regulating the flow ofwater and, if necessary, by varying the speed of drive of the variousconveyors employed the degree of hydration of the lime may be varied asdesired and regulated with great nicety.

in the drawing 1 have indicated means for driving the variousconvi-iyers, comprising a belt-wheel 8 on theshaft of conveyer7, gears 9and 1.0, comn'mnicating motion from conveyer 7 to conveyer 5, andsprocket-gears 11 and 12 and a drive-chain 14-, communicating motionfrom conveyer 5 to conveyor 2; but obviously many different ways ofdriving the several conveyors may be devised.

17 designates the outlet .for the completelyhydrated lime. The limedischarged there- IIO from, which will be completely or partiallyhydrated, according to the amount of water added, may then be put up inpackages or mixed with plaster, cement, sand, &c., for the making ofready-mixed plaster, mortar, and the like, or may be utilized ordisposed of otherwise.

Cement and other substances requiring hydration may be treated in thesame manner, except that the water is preferably added to limy cementsin the form of a dust-spray, pipe 15 being provided with suitabledevices for producing this character of spray.

I intend the term cementitious material where used in the followingclaims to be generic both to cements proper and to plasters and otherwater-setting plastics.

That I claim is 1. The process of slaking quicklime to a dry conditionwhich consists in moving a body of such lime through and beyond a zoneof water-supply before hydration to a material extent takes place insuch body, supplying water to the lime while in said zonein amountmerely sufficient to slake it to the desired extent, and thereaftercontinuing the forward movement of the lime and simultaneously stirringit while hydration continues.

2. The process of slaking quiclilime which consists in movingabody ofsuch lime through and beyond a zone of water-supply before hydration toa material extent takes place in such body, supplying water to the limewhile in said zone in amount insufficient to completely slake it, andthereafter continuing the forward movement of the lime andsimultaneously stirring it while hydration continues.

3. The process of slaking quicklime which consists in movinga body ofsuch lime through and beyonda zone ofwater-supply before hydration to amaterial extent takes place in such body, supplying water to the limewhile in said zone in amount just sufficient to slake the major part ofthe lime, and thereafter continuing the forward movement of the lime andsimultaneously stirring it while hydration continues.

4. The process of slaking quicklime which consists in moving a body ofsuch lime through and beyond a zone of water-supply before bydration toa material extent takes place in such body, supplying water to the limewhile in said zone in amount suflicient to slalze in excess of sixty percent. of the lime but insufficient to slalie the latter completely, andthereafter continuing the forward movement of the lime andsimultaneously stirring while hydration continues.

5. The process of slaking quicklime which consists in moving a body ofsuch lime through and beyond a zone of water-supply bcforehydration to amaterial extent takes place in such body, supplying water to the limewhile in said zone in amount merely suflicient to slalze it betweenapproximately three-fourths to four-fifths of complete hydration, andthereafter continuing the forward movement of the lime andsimultaneously stirring it while hydration continues.

6. As an article of manufacture, a dry shortslalied lime, comprisinglime uniformly slalzed to in excess of sixty percent. of completehydration, but not completely slaked.

7. As an article of manufacture, a dry shortslaked lime, comprising limeuniformly slaked to between three-fourths and four-fifths,approximately, of complete hydration, but not completely slaked.

In testimony whereof I afiix my signature in the presence of twowitnesses.

CARLETON ELLIS.

-W'itnesses:

HARRY M. MARBLE, D. HOWARD l-lAinroon.

